As known, electrical motor apparatuses comprise a portion mounted on a rotating shaft, called rotor, and a fixed portion, called stator. An appropriate first compartment of the electrical motor apparatus, or motor compartment, houses the stator and rotor, so as to be separated from the external environment. A second compartment of the electrical motor apparatus, or collector compartment, coupled with the motor compartment, houses, on the other hand, the electrical connections used for starting the motor. The rotating shaft extends lengthwise along the electrical motor apparatus passing through the collector compartment and the motor compartment; the end of the rotating shaft opposite the collector compartment comes out from the motor compartment to drive a load associated with the electric motor, that could be, for example, an industrial machinery.
Usually, the electrical motor apparatus comprise a cooling system adapted to dissipate the heat generated by the stator and rotor inside the motor compartment and by the electrical connections inside the collector compartment. Such cooling system comprises one or more paths created for flowing a cooling fluid.
The cooling of the collector compartment is particularly critical, as the reaching of temperatures higher than 80-100° C. inside of it may compromise the proper operation of those members for the electrical connection with a power supply source, required to start the motor. As an example, the excessive heat in the collector compartment may damage the contact between the brushes and the collector rings mounted on the rotating shaft to slide on the brushes. A non-optimum contact between the brushes and the collector rings may cause, upon the passage of current therein, the occurrence of phenomena that can damage or still decrease the lifetime of collector rings, such as for example, the appearance of sparks.
Currently, electrical motor apparatuses comprise cooling systems that, although adequately performing functions and applications that they are supposed to carry out, still exhibit some aspects susceptible to improvements, in particular for what is concerning the dissipation efficiency of the overall generated heat, and most especially in the collector compartment. Even the arrangement, configuration and versatility of the members composing the cooling system are susceptible to improvements.
As an example, a cooling system of a known type comprises a first pipe heat exchanger that is coupled with and extends lengthwise along the motor compartment, and a second pipe heat exchanger that is coupled with and extends lengthwise along the collector compartment. Alternatively, a single pipe heat exchanger that is coupled with and extends lengthwise along both the motor compartment and the collector compartment may be used.
Pipe inlet openings of the two heat exchangers are in communication with the environment outside the electrical motor apparatus; in particular, the inlet openings of at least one group of pipes of the first heat exchanger are in communication with the environment, through coupling with pipes of the second heat exchanger.
The cooling system comprises means adapted to force inside of it a cooling air flow constituted by air collected from the external environment, flowing from the pipe inlet openings of the two heat exchangers towards the pipe outlet openings of the first heat exchanger. In this way, the surfaces of the pipes are thermal exchange surfaces, through which the heat generated inside the compartments of the electrical motor apparatus is transferred to the cooling air that progressively warms up along its path.
In case of horizontally mounted electrical motor apparatus (that is, with the rotating shaft parallel to the supporting surface whereupon the electrical motor apparatus is mounted), the cooling system comprises a fan mounted on the end of the rotating shaft coming out from the motor compartment in a way opposite to the collector compartment; such a fan is operatively connected to the pipe outlet openings of the first heat exchanger, so as to force the cooling air flow previously described. The fan must be positioned at a certain distance from the opening through which the rotating shaft comes out from the motor compartment to drive the load, such as to allow the correct passage of the cooling air flow. Such distance imposes a constraint to the overall sizing of the electrical motor apparatus.
In case of vertically mounted electrical motor apparatus (that is, with the rotating shaft transverse to the supporting surface whereupon the electrical motor apparatus is mounted), the fan cannot be mounted on the rotating shaft, such as in the horizontal installation, for stability reasons; the cooling air flow is hence generated through one or more auxiliary modules of the electrical motor apparatus, comprising, for example, fans driven by external electric motors; the presence of such auxiliary devices negatively impacts the cost, maintenance and installation simplicity of the electrical motor apparatus.
The main task of the present invention is to realize an electrical motor apparatus having a cooling system capable of overcoming the above-mentioned drawbacks, and in particular, that with regard to known solutions, might more efficiently dissipate the heat produced inside the collector compartment.